1. Field of the Invention
The present invention relates to liquid cargo vessels generally and, more particularly, but not by way of limitation, to a liquid cargo vessel of novel, simplified design and novel method and apparatus for the construction thereof.
2. Background Art
Liquid cargo vessels have been used for years for transporting liquids such as petroleum and the products thereof. Recent regulations have required that vessels for the transportation of petroleum and petroleum products will be of double hull constructions and that single hull vessels will be retired. The theory of such requirement is that double hulls will minimize the discharge of the contents of the vessels in the case of grounding or collision.
Double hull vessels are constructed of joined sandwich sections with inner and outer hull portions joined and spaced apart by longitudinal and transverse plates disposed between and welded to the inner and outer hulls. In the typical building of such hulls, a hull plate is placed on a horizontal surface and several longitudinal plates are placed vertically on the hull plate and are simultaneously robotically welded to the hull plate. Transverse plates are then joined between the longitudinal plates. A problem with this method of construction is that the simultaneous welding of all the longitudinal plates can distort the hull plate and/or create built-in stresses.
Another disadvantage of conventional double hull construction is that the transverse plates make inspection, painting, and/or repair of the spaces between the inner and outer hulls difficult, since the inspector and workmen have to crawl through manholes disposed in the periodically occurring transverse plates.
A further disadvantage of conventional double hull construction is that the sandwich sections are non-uniform, with a section for one portion of a midbody being different from a section for another, yet similar, portion of the same midbody. This type of construction together with other features of conventionally constructed double hulls result in a non-uniform structure having a relatively high degree of complexity of construction, with the concomitant high labor content in the cost of constructing a double hull vessel.
An additional disadvantage of conventional double hull construction is that there is a high probability of crack occurrence at intersecting points of transverse and longitudinal framing.
Accordingly, it is a principal object of the present invention to provide a midbody section for a double hull vessel that is simple in design and economically constructed.
It is a further object of the invention to provide such a midbody section for a double hull vessel that does not require transverse reinforcing plates between the inner and outer hulls.
It is an additional object of the invention to provide a method and apparatus for the construction of such a double hull vessel.
Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.